Abstract
For several decades, scientists have been aware of significant benefits allowing quantum information processing technologies to surpass their classical counterparts. Recent technological development allows these benefits to be tested experimentally and in some cases also implemented in practical devices. So far the majority of experimental quantum networks was limited to peer-to-peer communications between two parties. Practical implementation of quantum communications networks, however, needs to address the problem of scalability to serve large numbers of users. Similarly to classical computer networks, their quantum counterparts would require routing protocols to direct the signal from its source to destination. Devices implementing these routing protocols are called quantum routers and have recently been subject of an intense research. In this paper, we report on experimental implementation of a linear-optical quantum router. Our device allows single-photon polarization-encoded qubits to be routed coherently into two spatial output modes depending on the state of two identical control qubits. The polarization qubit state of the routed photon is maintained during the routing operation. The success probability of our scheme can be increased up to 25% making it the most efficient linear-optical quantum router developed to this date.
Highlights
For several decades, scientists have been aware of significant benefits allowing quantum information processing technologies to surpass their classical counterparts
We report on an experimental implementation of a linear-optical quantum router based on our original theoretical proposal[1]
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Summary
Scientists have been aware of significant benefits allowing quantum information processing technologies to surpass their classical counterparts. To classical computer networks, their quantum counterparts would require routing protocols to direct the signal from its source to destination. Devices implementing these routing protocols are called quantum routers and have recently been subject of an intense research. The quantum routing transformation belongs to a broader class of quantum state fusion protocols[2] with the requirement to use spatially separate output ports. A general quantum state fusion protocol implemented by Vitelli et al.[2] meets all the requirements for a quantum router, but was not designed as such and operates with a rather low success probability of 1/8 (while applying feed-forward corrections).
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